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blk-mq: fix racy updates of rq->errors

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blk_mq_complete_request may be a no-op if the request has already
been completed by others means (e.g. a timeout or cancellation), but
currently drivers have to set rq->errors before calling
blk_mq_complete_request, which might leave us with the wrong error value.

Add an error parameter to blk_mq_complete_request so that we can
defer setting rq->errors until we known we won the race to complete the
request.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagig@mellanox.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Christoph Hellwig
2015-09-27 21:01:50 +02:00
committed by Jens Axboe
parent 60de074ba1
commit f4829a9b7a
8 changed files with 32 additions and 34 deletions
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12
block/blk-mq.c
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@@ -393,14 +393,16 @@ void __blk_mq_complete_request(struct request *rq)
* Ends all I/O on a request. It does not handle partial completions.
* The actual completion happens out-of-order, through a IPI handler.
**/
void blk_mq_complete_request(struct request *rq)
void blk_mq_complete_request(struct request *rq, int error)
{
struct request_queue *q = rq->q;
if (unlikely(blk_should_fake_timeout(q)))
return;
if (!blk_mark_rq_complete(rq))
if (!blk_mark_rq_complete(rq)) {
rq->errors = error;
__blk_mq_complete_request(rq);
}
}
EXPORT_SYMBOL(blk_mq_complete_request);
@@ -616,10 +618,8 @@ static void blk_mq_check_expired(struct blk_mq_hw_ctx *hctx,
* If a request wasn't started before the queue was
* marked dying, kill it here or it'll go unnoticed.
*/
if (unlikely(blk_queue_dying(rq->q))) {
rq->errors = -EIO;
blk_mq_complete_request(rq);
}
if (unlikely(blk_queue_dying(rq->q)))
blk_mq_complete_request(rq, -EIO);
return;
}
if (rq->cmd_flags & REQ_NO_TIMEOUT)